The invention relates to a process for the surgical treatment of the eye by perforation, by laser radiation, of a tissue or inner wall of the eyeball having a resistance to the free circulation of the aqueous humour. Such a method may be utilized for the treatment of eyeball diseases such as glaucoma in which the perforation of an inner wall of the eyeball is able to give the patient a substantial and swift improvement in health.
Glaucoma is an eye disease which is characterized mainly by an increase in the intra-ocular pressure. As is known, the intraocular pressure for the eye of a human in good health is comprised between 15 and 16 mm of mercury. In the case of a disease of the glaucoma type, the intra-ocular pressure of the eye afflicted by such a disease is more often above 20 to 21 mm of mercury and in the course of daily variations can reach, more often than not, pressures that are higher than the above mentioned pressures and variable according to the type of glaucoma. This excess pressure and its variations have as a consequence, in the end, the destruction of the optic nerve. The clinical symptoms, which are not very pronounced in the early stages of such a disease, are characterized mainly by a generally slow and progressive narrowing of the field of vision and by an insular degradation of the latter, ending in a total loss of vision in the absence of treatment.
Recent studies of epidemiology of glaucoma have shown that in the majority of industrial countries such a disease was the main cause of blindness. In Western Europe and the United States an ailment of this type attacks an average percentage in the order of 2% of individuals aged 40 years or more. In 60% of the cases of such a disease the outcome, if not treated, is inevitably blindness.
Other recent studies have revealed that in patients affected by diabetes, the average percentage of the existence of a disease of the glaucoma type was 16%.
The main different forms of glaucoma can be listed in the following way, their common primary cause appearing to be a localised resistance to the free circulation of the aqueous humour on the level of a determined location of the usual circuit of the aqueous humour between the posterior chamber and the anterior chamber of the eye or in the angle of the anterior chamber of the eye, the aqueous humour then normally reaching at this stage the vein system. The first effect of this increased resistance is an increase in the intra-ocular pressure of the eye and finally the appearance of the symptoms of glaucoma.
The primary glaucomas are:
Chronic glaucoma simplex or glaucoma angulo aperto which is generally characterized by an open irido-corneal angle. The zone of localized resistance to the free circulation of the aqueous humour is in this case situated on a level with the inner wall of the canal of Schlemm, the so-called trabecular meshwork, which separates the canal of Schlemm from the anterior chamber of the eye nearby the irido-corneal angle. The intra-ocular pressure in this case is above 22 mm of mercury and can exceed 40 mm of mercury. This kind of glaucoma also includes glaucoma capsulare and pigment glaucoma; PA1 glaucoma with closed angle or glaucoma acutum angulo obstructo which is generally characterized by a closed irido-corneal angle, the iris on a level with the irido-corneal angle exerting a pressure on the inner wall of the canal of Schlemm causing, by closure, a resistance to the flow of the aqueous humour. This kind of glaucoma includes intermittent glaucoma in which closure is not permanent, the increase or decrease of the aqueous humour pressure occuring according to the iris-root position relative to the irido-corneal angle; PA1 mixed glaucoma which is a combination of the above two types; PA1 infantile glaucoma (Hydrophtalmus, Buphthalmus) which are to be related with congenital "failure". Generally this congenital failure consists of an abnormal deposition of embrionary substance on the irido-corneal angle inner walls. PA1 Some of them are to be related to an inflammation of the supraciliary space and of the iris, such an inflammation leading generally to a sticking of the iris-root with the inner walls of the anterior chamber of the eye thereby giving use to a possible increase of the aqueous humour pressure. PA1 Others are to be related to the inflammation and swelling of the inner walls of the anterior chamber of the eye which leads also to an increase of the resistance to the free circulation of the aqueous humour. PA1 Others one, the so-called glaucoma by obstruction of the pupillary block, arise from the peripheral sticking of the iris on the crystalline lens or on the front part of the vitreous humour when the crystalline lens has been removed. PA1 Closing of the pupil through a membrane due to an inflammation (occlusion pupillae) will also lead to a particular secondary form of glaucoma.
Other forms of glaucoma can also be analysed; these are often so-called secondary forms as they are linked to other illnesses.
Different approaches of therapeutic treatment of glaucoma have been proposed until now.
One method of therapeutic treatment by medicaments consists in controlling the intra-ocular pressure of the eye by local, oral or parenteral administration of medicaments as for example the medicament known by the name "Diamox". These methods have a limited use because on the one hand their effect is often not certain and, on the other hand, this effect is often not lasting in the long term.
Another method of therapeutic treatment by direct surgical intervention can also be envisaged. However, such a technique presupposes a first class hospital sub-structure, a very high qualification on the person carrying out the operation, and in any case allows success to be achieved in only a percentage of cases varying between 40 and 92% according to the type of intervention.